I didn't use a bit on him all summer and fall and only just started using one again for training. He's not foaming up, but I'm keeping an eye out for that. However, he is pulling his lips back after I put the bridle on and often when I'm riding, whether or not I'm making any contact with the reins. He also chews on the bit a lot. The pictures below aren't of my horse, but are good examples of how he used to foam up last Spring before I switching him to being bitless and how he still continues to pull his lips back.
I'm thinking of getting a French Link Snaffle, maybe even copper, but have never had bit issues before so don't have a lot of experience solving them.